The present invention relates to a method for manufacturing a mechanical seal provided with a cemented carbide hardened ring.
In modern industrial fields, various types of mechanical seals have been developed and used to solve various kinds of problems related to sealing.
Such mechanical seals vary in shape corresponding to their function and construction. Furthermore, in terms of raw materials for mechanical seals, various combinations can be considered.
Plastics, hard rubber, carbon, Hastelloy, ceramics and cemented carbides are considered as materials for the mechanical seal.
Among the above-mentioned materials, cemented carbides have especially been used in combination with carbon rings since they have favorable mechanical properties and wear-resistant property. In manufacturing such rings conventionally, a cemented carbide ring of a carbide group is primarily produced by a powder metallurgy method. The product is then ground and soldered to the iron base alloy substrate and finally is ground and polished.
In the above conventional manufacturing method, the cemented carbide ring is primarily produced. Therefore, although the mechanical seal requires the cemented carbide layer of 1 mm thickness, the green compact for such cemented carbide must be more than 3 mm thick in view of the deformation during sintering and the margin of the sintered compact for grinding. Furthermore, after the cemented carbide ring is soldered to a groove of an iron base alloy substrate, the cemented carbide must be ground to a desired thickness. Accordingly, the yield rate of materials becomes extremely low in terms of raw material.
Furthermore, problems still remain unresolved in view of labor and cost for manufacturing, the adhesion strength of the soldering, and errosion.
It is an object of the present invention to provide a method for manufacturing a mechanical seal ring which can resolve the afore-mentioned problems.
It is another object of the present invention to provide a method for manufacturing a mechanical seal ring which can impart firm and strong metallurgical bonding between the cemented carbide hardened layer and the substrate.
It is still another object of the present invention to provide a method for manufacturing a mechanical seal which can readily provide the cemented carbide layer onto the groove of the substrate thereby considerably reducing the manufacturing cost.